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Dunstall Motorcycles
1971 Dunstall Norton Sleeper


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The sleeper model is basically a stock Norton Commando with the Dunstall Exhaust System being the only outward sign of it's considerable performance. Internally it is given the full Dunstall treatment and with 68 bhp on tap, it will out-drag anything your are likely to come up against.

Engine Specification

  • Bore 73mm Stroke 89mm
  • Capacity 745cc
  • Re-sphered & machined combustion chambers
  • Steeper valve angle (Inlet) 26½°
  • Enlarged hand finished and polished ports
  • Special H 18 S material valves 1 5/8" inlet
  • Bronze Hi-Dural valve guides
  • Special dual rate springs
  • Enlarged induction manifolds
  • 10:1 compression spun cast pistons
  • Lucas capacitor ignition system
  • Paired Amal 932/901 type concentric carburettors
  • Flexible forced oil feed to rockers
  • Wide heat range spark plugs
  • Output 68 Bhp at 7000

Gear Ratio Options

Four speed semi-close ratio

Overall Gearing
Ratio Max Speed
4.84 115 mph
4.56 121 mph
4.38 125 mph
4.15 133 mph

Five Speed Close Ration optional extra

www.woodgate.org/dunstall/71nor4.html / Webmaster / Revised 24th February 2000